> Desalination processes produce large quantities of brine, possibly at above ambient temperature, and contain residues of pretreatment and cleaning chemicals, their reaction byproducts and heavy metals due to corrosion.[45] Chemical pretreatment and cleaning are a necessity in most desalination plants, which typically includes prevention of biofouling, scaling, foaming and corrosion in thermal plants, and of biofouling, suspended solids and scale deposits in membrane plants.[46]
> To limit the environmental impact of returning the brine to the ocean, ...
> Brine is denser than seawater and therefore sinks to the ocean bottom and can damage the ecosystem. Careful reintroduction can minimize this problem. Typical ocean conditions allow for rapid dilution, thereby minimizing harm.
What's an example of not typical?
Here's an article which points out that the Arabian Gulf is shallow, with low circulation rates and high evaporation rates which make it naturally saltier. That, combined with the damming of freshwater and increasing number of desal plants places a limit on to how much it can be use as a water source: http://www.thenational.ae/news/uae-news/environment/desalina...